It has long been recognized that trouble-free operation of an internal combustion engine requires some form of filtering of the fuel consumed by the engine. In particular, the absence of high standards of quality control in diesel fuel supplies dictates that an effective fuel filter be incorporated into the fuel supply system for a diesel engine. It is not uncommon for diesel fuel to contain significant quantities of abrasive particles and water. The abrasive particles present the potential for permanent damage to components of the fuel injection system. The abrasive particles can adversely affect the performance of the fuel injection pump by destroying the ability of the fuel injection pump to precisely meter and deliver fuel at high pressures. The presence of water in the diesel fuel supply can cause corrosion of engine components, and during freezing conditions, can result in interruption of the fuel injection system and/or seizure of moving components.
A number of conventional fuel filter systems perform the dual functions of removing particulate matter from the diesel fuel and separating water from the fuel. Prior art fuel filters have typically been constructed in the form of a metal can, permanently enclosing the filter element in a single use assembly. While these assemblies have proved to be effective and reliable, they are less than ideal in terms of waste of materials and disposal cost. The filter cartridge surrounds and supports a filter element typically constructed of an accordion folded pleated, cylindrical arrangement of filter media, which is usually a paper-like composite of selected fibers, chemically treated to reject water. The pleated cylinder of filter media is typically secured to end caps at each end by adhesive or the like, forcing fluid through the filter media before flowing on to the fuel handling systems.
Conventionally, the disposable filter cartridge is replaced at pre-established intervals of filter usage. In practice, the filter cartridge requirements may vary depending upon such characteristics as the type and make of the internal combustion engine, the specific applications for which the engine is employed, the climate in which the combustion engine is operated and/or regional characteristics as to the quality of the fuel supply. The filter cartridges thus commonly vary as to their dimensions, their capacity, and the qualities of their filter media.
Due to the poor quality of diesel fuel found around the world in off-road (off-highway) applications, it is very common to see a fuel filter media plug with various degrees of oxidized fuel, water, asphaltenes, and organic debris that can create sludge on the surface of the filter paper. As this sludge accumulates, choking off the pore of the media, a differential pressure accumulates across the filter paper. When the differential pressure becomes sufficiently great that the paper cannot support the forces acting on it, the paper is prone to buckling, twisting and ultimately rupture, effectively destroying the filter's ability to function. In order to prevent twisting, buckling and rupture of the filter paper, it is very common in the filtration industry to use a support tube on the inside core of the filter media and extending between end caps at either longitudinal end of the pleated cylinder of filter media. This tube is most commonly plastic or steel, with perforations to allow flow through the tube. While this solution is effective, it adds to the total cost of the filter element, and depending on the size of the perforations, it can cause localized high velocity spots of the filter paper which can lead to some small losses in filter performance.
One of the problems that is frequently encountered in connection with replacement of the filter cartridge is ensuring that the replaced cartridge is compatible with the filtration requirements for the fuel system. Because numerous types and qualities of filter cartridges may dimensionally conform to the base of a given filter system, the replacement filter cartridge frequently does not comply with the specifications for the filter system, thereby jeopardizing the integrity of the fuel filtering system. Use of an incompatible filter cartridge can have very serious effects on the operation of the internal combustion engine, and may also be unnecessarily expensive when a less costly cartridge is fully suitable. Frequently, either the owner or the maintenance personnel servicing the internal combustion engine are totally unaware of the replacement filter cartridge specifications and requirements and unknowingly jeopardize the integrity of the filtering system by using non-conforming filter cartridges. There are also instances where inferior or improper replacement filter cartridges are intentionally installed without the knowledge of the owner or operator of the vehicle.
Increased awareness of environmental protection and recycling of materials have led to a need for more efficient filtration systems having a minimum disposable component. In addition, environmental protection agencies seeking to reduce the volume of waste items associated with the automotive and trucking industries may no longer permit unrestricted disposal of used fuel filters into the normal waste stream, thereby necessitating specialized and consequently more expensive disposal.